


The Sister Sickness

by disfanatic10



Category: Marvel Cinematic Universe, Spider-Man (Tom Holland Movies)
Genre: Peter Has a Sister, Sick Peter Parker
Language: English
Status: Completed
Published: 2020-01-05
Updated: 2020-01-05
Packaged: 2021-02-27 07:48:46
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,008
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22123615
Author URL: https://archiveofourown.org/users/disfanatic10/pseuds/disfanatic10
Summary: Peter enlists Bruce’s help in helping him save his long-kept secret- his sister Payton, who also has super powers. And maybe, he’ll need Bruce’s help to save himself too.
Relationships: Bruce Banner & Peter Parker, Peter Parker & Original Female Character
Kudos: 13





	The Sister Sickness

It was no surprise that Peter being at the tower had basically turned the Avenger's world upside down. He had definitely turned Dr. Banner's world upside down, as he was now the unofficial caretaker of a very-accident prone super teen with approximately no self-preservation instincts. Granted, he had gotten better, but there was still a long way to go. Every day, he thought Peter had to be out of surprises, and yet every day he somehow managed to surprise him even more. 

But one day, Bruce's world was turned inside out and backward, when Peter dropped from the Medbay ceiling with a "Dr. Banner, can you keep a secret?"

Bruce jumped. "Peter, what were you doing up there?"

"Waiting for you," the teen replied. 

"Why, what's it this time?" He asked teasingly. Peter was in here practically every other day with something. But Peter didn't laugh, or even crack the "ha ha so funny you're making fun of someone who's sick all the time" smile. 

"Pete, what is it? Are you sick?" Peter didn't answer, and instead looked at the ground. Bruce reached out to put a hand on Peter's forehead, but Peter moved out of the way. Bruce gave him The Eye. They had talked about Peter avoiding him when he was sick. 

"It's not me, I swear." He was silent again, seeming to mull words over in his head. 

"Then what is it?" 

"It's my sister."

Bruce stared at him for several minutes. Finally Peter spoke. "Pick your jaw off the ground, Dr. Banner."

He blinked at Peter. "You have a sister." He still sounded dazed. 

"Yeah, but no one really knows about her. That's why I asked you if you could keep a secret." 

Bruce still felt like he was moving in slow motion. "Does Tony know?"

"No!" Peter shouted. He said quietly. "And you can't tell him. I don't want anyone to know about her. I didn't even really want to tell you, but I have no choice."

"Why tell me then? If she's sick, why not just go to a normal doctor?"

Peter looked down again. "She's like me."

Bruce picked his jaw up off the floor for the second time in about 5 minutes. "So to recap, you have a sister, and she has superpowers too?"

"Yeah," Peter said.

"So what to you want me to do?" 

"I need you to figure out what's wrong with me." A voice said, and then another Spider-Man dropped from the ceiling. Bruce jumped. And then he started again, because he realized the voice hadn't even spoken, but instead had responded in his head.

"You're..." 

"Yes, I'm Peter's sister. And yes I'm a telepath. My name's Payton." Bruce shook his head. This was definitely a weird day. Even with the Avengers, communicating mentally was a new experience for him. 

"So, um, how...?"

"When our parents died, we were only about 3, and May couldn't take both of us. So she got Peter and her brother got me. May's brother works on Broadway, and I've been a dancer all my life pretty much. I go by Payton Ridley, so no one would possibly associate us. But I mean if you see us side by side, it's almost impossible not to see the resemblance."

"Well I'm not seeing it right now," Bruce snarked.

"Oh right," both Payton and Peter said, and Payton pulled the Spider-Man mask off and tossed it back to her brother. "Thanks for letting me borrow that, it's fun to stick to walls."

"See I told you, you should come patrolling with me sometime, but noooo, it's always 'I have rehearsal.'"

"Hey, it's a busy life being a broadway star."

"Must be for one who can't even sing," Peter fired back. This whole exchange was done mentally, and Bruce looked back and forth between the two while they did this, noting the way they both held themselves, the way her brown curls fell exactly the same way Peter did, how both of their bodies were extremely skinny but muscular. It was impossible not to see how alike they were. He couldn't believe Peter had kept this big of a secret for so long. Looking at the two of them was like looking at two halves of the same coin. 

Bruce realized he was staring and awkwardly cleared his throat. "So, um, what's wrong?"

"Oh right, I guess that is why I came here," Payton thought flippantly at him.

Wow, Bruce thought, she even got the Parker sass. In response, Payton raised her eyebrow. But then her face turned serious and she shrugged, looking at Peter to explain.

"She thinks...she thinks the spider bite is becoming more potent, that it's starting to destroy her—us—from the inside out."

"What can I do? Strange would be a lot more qualified to handle this than me, are you sure you don't want me to call him?"

"No." Peter said quietly. "We want you. Now c'mon, we need to get out of here, I can't keep FRIDAY hacked for very long."

"Why do we need to get out of here?" 

Peter gave Bruce a look. "For a man with 7 PHD's, you're not picking up very fast. No one can know about her, and since she might be dying, I need you to figure out what's wrong. Now either come willingly or I'm kidnapping you." Peter's voice was hard, and Bruce could tell he was serious. He clearly cared deeply about his sister.

Bruce shrugged. He was a doctor, after all, and he cared about Peter. The least he could do was care for his sister too. "Lead the way," he responded.

-time skip-

"So what are your symptoms?" Bruce asked. They had gone back to a small apartment in downtown New York. 

"Well, I get dizzy a lot, and my eyesight has gotten bad, but all my other senses have gotten way worse. I feel nauseous sometimes too, and like I'll get these random burning sensations."

Bruce thought. He had never really heard of anything like this, unless it was some sort of toxin. "Can I take a blood test?"

Peter's head shot up. "No! You can't run anything through FRIDAY! Mr. Stark will know then!"

"Why is it so imperative that Tony doesn't know? Clearly your uncle knows about you." Bruce gestured to several pictures around the room where Peter and Payton had their arms around each other and were grinning their identical smiles at the camera. There was a selfie on top of the Empire State Building (like literally on top on top, being Spider-Man had its advantages) and several pictures taken of them in Times Square and at several Broadway shows. (Peter would never tell anyone at the tower because they would make fun of him, but he absolutely adored Hamilton and Dear Evan Hansen. He knew every word to the Spongebob musical and had gotten front-row tickets when Hadestown came out. And of course he had made a special guest appearance at Spiderman Turn Off the Dark. Payton had totally gotten him hooked on Broadway musicals ever since that first performance of Little Shop of Horrors she had dragged him too.) 

Peter gestured wildly. "He's a civilian. It doesn't matter if he knows of my existence, he doesn't know I'm Spider-Man. But you guys, you're superheroes! Our life is dangerous! And I don't want her dragged into that. She has never been classified as a mutant, and she won't ever be as long as I'm here. She deserves a better life." Peter said this so emphatically that Bruce was taken aback. 

"I won't run it through FRIDAY, I promise. But it'll take longer to get the results that way."

"That's ok," Peter said. Suddenly he felt a pushing in his mind and looked at his sister.

Don't I get a say in this? She asked. It's my life. What are you going to do if the results come back that I am dying? What are you going to do then? He's not even a true medical doctor, he's not fully equipped to deal with what it could mean if what I think is happening really is happening. But it sounds like Tony, and this Strange guy, and Shield, might actually be able to find a cure. And how are you going to explain to them that it's affecting you as well? How have you managed to hide that from them? You might not be progressing as fast as I am, but I know you feel the pain too, and that your immune system is basically breaking down. Sooner or later they're gonna figure it all out, and then what? By then, it might be too late. Pete, you don't believe me, but people need you. The world needs Spider-Man, and May and Me and Tony and Bruce and Ned and MJ need Peter Parker. So if you don't tell Bruce, I will. You'll always look out for other people, but you need to have someone looking out for you. That's where I come in. I'm going to get you help, and if it means I get exposed as a mutant, so be it. I wanted a normal life, but this is more important. I know you need me, and I need you, and that's why I'm going to do this. You'll forgive me when we're both alive. Sorry Pete.

Peter heard the words, but his brain grew foggy. Why would I need to forgive you? He thought, but then he thought no more. Darkness began to close in, and the last thing he saw was the wood floor slowly coming toward his face.

I need to take them both to Avengers tower. Bruce thought. But that was weird, hadn't he been supposed to not do that... but it didn't matter. He had to do this. Both teens had just slumped over in a dead faint, he had to get them help. This become his one all-consuming thought as he texted Tony to send three suits. Tony texted him back almost instantly, asking why three!? 

But Bruce didn't reply. Tony would find out soon enough, and when he found out his Spider-baby was sick, there'd be hell to pay. And as for the girl, she was important. He couldn't remember exactly why, but it didn't matter. 

Bruce checked their pulses and waited for the suits. He was only concerned about getting them back safely. He didn't even notice that the thoughts in his head weren't his. 

-time skip-

"What the hell happened? And who the hell is she?" Tony practically screamed at Bruce the second he came in the door. 

"They both just...fainted all of the sudden." Bruce still sounded dazed. 

"Why were you with them? Who is this? Bruce? I need answers!" Tony took his friend by the shoulders and shook him. Bruce shook his head and his eyes seemed to clear.

"This is Payton. She's Peter's... friend. I think she might be a mutant too."

Tony just looked at him in astonishment. Bruce was not answering any of his questions, he was only creating new ones. He looked at his friend closely, noting the hesitant words and the slow movements. "Are you... being mind controlled?" 

"Maybe?" Bruce asked, sounding for just a second like himself. "But it doesn't matter. People are sick. I need to help them. I need to help Peter."

Tony seemed to remember the graveness of the situation then, as he viewed the two teens on the bed. They look so much alike, he thought, but then he scoffed at that idea, chalking it up  
to the weird lighting in the Medbay. Obviously Peter couldn't be related to this girl in any way.

"I'm going to run some blood tests and see what's going on. Tony, you need to leave the room. There could be potentially toxic chemicals in their blood, and I don't want you exposed."

Tony didn't move. "Bruce, I literally had palladium poisoning, I think I can handle some spider-bite mutations." 

Bruce knew better than to try to fight Tony's stubbornness. "Fine, but suit up." He gestured to a containment suit hanging on the wall. 

Bruce ran through several tests, drawing blood from the two unconscious teens and analyzing the blood. He sent the results to Friday, and it beeped as it finished. "Would you like me to read the results?" The AI asked. 

"Yeah, sure." Bruce nodded mindlessly, but even as he did that, he felt like it was the wrong decision. "Actually, never mind..." but FRIDAY had already started, so Bruce trailed off. 

"Both Peter and his biological sister appear to be suffering from delayed muscular and bone pains. Their bones are beginning to hollow out, making their body composition similar to that of a spider, which has no bones. Their blood is mutating rapidly, changing into a venomous secretion. Payton is further along than Peter, as her body is not as highly trained, and her healing factor is less than Peter's. Without treatment, she will likely last less than a week, and Peter has maybe a week beyond that."

Bruce tried to keep a handle on the situation, "what would you suggest is the best course of treatment—" He cut off rapidly as he heard a thump behind him. He turned to see Tony unconscious on the floor. "Oh, shit!"

The doctor ran to Tony's side and checked his pulse. "Tony? Tony wake up!" Sighing, Bruce told FRIDAY to alert Steve. When the Captain arrived, Bruce explained what happened. "Tony found out some surprising information, and he passed out from the stress. Can you help me carry him to a bed? He'll be fine in a little while, this has happened before. I need to take care of Peter and Payton."

"Peter and...?" Steve looked over at the two kids in the bed. "She's his sister?" 

Bruce looked surprised that he had figured it out so quickly. "Yeah, and she's superhuman too. They're also both apparently..." he couldn't finish the sentence.

Steve understood and gently put his hand on Bruce's shoulder. "Well if they have you taking care of them, I'm sure they'll be fine."

"Thanks Steve." Bruce said softly, and the. He turned his attention back to FRIDAY and his patients.

"FRIDAY, what is the best course of treatment?"

"They will need an immediate blood transfusion. They both have B positive blood, and I have already contacted Bucky and Natasha, who both also have this blood type. Once the toxic blood has been flushed from their body, they will need repeated supplement injections to begin reversing the mutations in their DNA. Dr. Cho and Dr. Amsterdam, Shield's head medic, will be here shortly to assist."

At that moment, both Bucky and Natasha came running into the Medbay, with Sam and Wanda close behind. Bruce explained the situation to them quietly, and both Natasha and Buck quickly agreed to help. "We love Peter, and we'd do anything to help him, and if this is his sister, and a superhuman at that, we're going to help her too," Natasha eloquently put it. 

Bruce nodded with appreciation. He prepped them both for the procedure and began the first step of saving Peter and Payton. 

Thankfully, the transfusion worked, and their blood toxicity levels began to decrease. Bruce worked tirelessly in the lab, making the necessary drugs and taking care of the kids. Days passed without him realizing, and he only slept when one of the other avengers forced him to leave the lab, at which point he would basically collapse into a state of hibernation, and then wake up ready to do it all over again. Every day that passed and the kids didn't wake up made him lose more hope. But he couldn't give up. He had to save Peter. He remembered back after the Sokovia accords, when the team had almost fractured for good. Peter was one of the only reasons they were all okay with each other now. He had helped them all heal emotionally as much as Bruce physically helped Peter heal. He could not fail this kid. 

Bruce readied another dose of the healing agent and slipped it into their IV's. Methodically, he went through the process of checking their vitals, knowing nothing had changed. 

But something had changed. Both of their heart rates were increasing, as was brain function. Bruce's breath caught. Their stats were almost... normal. I have to tell Tony, he thought, but then he changed his mind. If it wasn't... he couldn't do that to the man. He would bide his time until he knew for sure. But when he turned back, he saw two pairs of matching blue eyes staring up at him. He rushed over. "You're awake." Bruce said incredulously. Peter just nodded. He couldn't speak, because Bruce had been forced to intubate them since the IV wasn't providing enough nutrients. He couldn't believe they were actually awake. He patted Peter's hand, and called Tony.

It took several weeks for them to make a full recovery, but eventually they were both up and walking again. Bruce had figured out how to selectively edit their DNA so they wouldn't have these problems again. Life slowly adjusted. Payton would come to the tower on some weekends, and she began fighting crime with Peter. They were careful to keep her identity completely hidden, but there was still the fear that someone would find her. However, they knew that no matter what happened, they would be strong. Payton had mental willpower of steel. After all, she basically had kept both of them alive by her pure belief that Bruce would save them. He had succeeded, and now their lives were completely changed. 

As soon as they woke up, the first thing Tony did was take his Spider-kid and his newly basically adopted daughter to a Broadway show. He even let them sing along to every single word of The Lion King. If that's what it took to make his kids happy, then he would do anything.


End file.
